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Permalink Reply by farmroast on April 19, 2011 at 8:08am

There tend to be a lot of variables bean to bean in DP ethiopians. Bean sizes, ripeness, varietals, moisture content. This will result in uneven roasting. This will also add character to the cup that can be desirable or not so. You can do a heavier pre and or post roast culling to adjust the cup outcome. 

Also consider that you will have more outliers on both ends of first crack. I will consider my timing point of start of first a little later due to early outliers and consider my stretch time at the slightly longer side of the range. Take your start of first BT and approx. finish temp. and divide by stretch time to consider your average BT RoR(rate of rise or delta bt). Say you have approx. 32degrees of rise to finish to be achieved in 3.5min. which would be about 9degree average/min. If you go to fast at start say 15degrees rise/min you might flirt with stalling later in the stretch to achieve the average and going to slow at start you may end up with a rather anemic early cracking. I try to have the first min. a little higher than the average, in this case about 12degrees/min. this would leave 20degrees over the remaining 2.5mins bring the average down to about 8. Be aware that the beans will tend to naturally try to speed up on the last min.+. 

I have live BT RoR monitoring on my setup which I find makes it much easier to monitor and manage the speed of the roast progression.

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Permalink Reply by nick placakis on April 19, 2011 at 9:08am

sound like you may want to let the coffee develope a little more before ending try a 4 min then a 5 min. 1st crack to end and cup them both and see what you get. There are some important questions that need to be asked first:

1-what is the charge temp.

2-at what temp. are you increasing airflow to the drum

3-how long is it taking you to get to around 270 degrees

 

The stalling may have affected the developement. your temp. should still gradually increase to the end of the roast if you need to slow it down try dropping the temp. about 30-45 seconds before 1st crack.

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Permalink Reply by Mike McGinness on April 19, 2011 at 2:45pm

I get the best results coming up hard to just before 1st is about to start (about 5f before) and slamming on the brakes. This allows for a good City with 3min start of 1st to end of roast development.

 

My question is, how are you applying the brakes? If it's just turning down the heat you haven't hit the brakes, more like hitting the clutch and coasting. No longer applying power but not braking. Gotta also reduce airflow to reduce convection, that is hitting the brakes.

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Permalink Reply by Paul on April 19, 2011 at 2:58pm

Thanks for the great advice Mike!! I never thought about reducing the airflow on this coffee. I will try that and see what I get. I am also going to take this coffee a bit darker to develop the body some more too. I will try this and let you guys know what I come up with.

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Permalink Reply by Mike McGinness on April 19, 2011 at 3:44pm

Controlling airflow is huge in controlling roast profiles. FWIW wouldn't fully judge a lighter Ethiopia roast until 10 to 12 days rest.

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